States of Matter • Solid (s) • Liquid (l) • Gas (g) • Aqueous (aq) – A solid dissolved in water solution – Example: NaCl(s) + H2O vs NaCl (aq) Predicting States of Matter Tips • The following are gases at room temperature: – Elements − hydrogen, nitrogen, oxygen, fluorine, chlorine – ammonia – carbon monoxide and carbon dioxide – nitrogen monoxide and nitrogen dioxide – sulfur dioxide and sulfur trioxide – hydrogen-compounds (e.g. hydrogen chloride and hydrogen cyanide) Tips • Acids are always aqueous. • Any phrases that refer to being dissolved or in solution means the compound is aqueous. • Liquids − bromine, mercury, and water • All other elements are solids. When in doubt, so are most other compounds, particularly ionic compounds. Composition and Decomposition Reactions • Must Use: – Common Sense – Tips – Ionic Compounds are solids – Molecular Compounds either liquid or gas – Diatomics usually gas Examples S(s) + H2(g) H2S (g) CuS Cu(s) + S(s) (s) 2 H O O2(g) + 2 H2(g) 2 (l) 2 KClO3(s) 2 KCl(s) + 3 O2 (g) Single Replacement AX(aq) + B(s) or (g) BX(aq) + A(s) or (g) Cu FeSO CuSO4(aq) + Fe(s) (s) + 4(aq) 2 KCl + I 2 KI(aq) + Cl2(g) (aq) 2 (g) Double Replacement • Reactants are always aqueous • Products are either: – One aqueous and one solid (ppt) – Both aqueous (soluble so no solid forms) Double Replacement – 2 types 1. Reaction of 2 ionic salts 2 KI(aq) + Pb(NO3)2(aq) 2 KNO3 + PbI2 Are any solids produced? Use a solubility chart to figure this out… Solubility Chart • s – Soluble, a solid will not form • si – Slightly soluble, a solid may form then dissolve, compound is solid • i – Insoluble, a solid ppt will form Double Replacement – 2 types 1. Reaction of 2 ionic salts 2 KI(aq) + Pb(NO3)2(aq) 2 KNO3 + PbI2 (s) Are any solids produced? Use a solubility chart to figure this out… Examples Na2SO4(aq) + BaCl2 (aq) BaSO4(s) + 2 NaCl(aq) NaNO3(aq) + KCl(aq) KNO3 + NaCl no ppt Double Replacement – 2 types 2. Neutralization Reaction: acid + base Acid(aq) + Base(aq) Water + Soluble Salt H2SO4(aq)+ 2 NaOH(aq) H2O(l) + Na2SO4 (aq) Combustion CO H O CxHy + O2(g) 2 (g) + 2 (g).